<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Strict//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<script >
function lazy_sum(arr) {
    var sum = function () {
        return arr.reduce(function (x, y) {
            return x + y;
        });
    }
    return sum;
}
 
var f = lazy_sum([1, 2, 3, 4, 5]); 
alert(typeof(f)) ;
alert(f()) ;

</script>


<body>








</body>
</html>